Olap4ld Metadata/Query Design
From Linked Data Cubes
On this page you find more information about design decisions for olap4ld metadata queries.
- Back to Olap4ld Metadata
- Is for metadata objects the schema result set used? - No, but both are fed by the same function "executeMetadataRequestOnLd".
- When are implicit objects such as dimension "Measures" created? - For Mondrian-XMLA, they are created within the XMLA server. Everything is basically created from the XMLA response. It should be similar for olap4ld, the Linked Data Engine should return List<Node> that are similar to the XMLA output. For rowset, we then do not have to transform anything. For metadata objects we need to use the available translations. The advantage would be that we do not need to define extra mappings from Linked Data to XMLA since those are encoded in the SPARQL queries, already. The only thing that we do is to transform the unique names to MDX applicable names.
- What do we do for rowset metadata? - We transform every value to compliant MDX and return the rows.
- What do we do to make literal values unique over dimensions? So far, we haven't had the case, but in case, we have to use the segment notation, which also means, we need to give every such member a segment notation name, which in turn means, we cannot do it via SPARQL.
See the following two UML sequence diagrams for a comparison of Schema Result Set Queries and Metadata Object Queries: